Sampling programs are often conducted in the oil field to reduce risk. For example, the more closely that a given sample of formation fluid represents actual conditions in the formation being studied, the lower the risk of inducing error during further analysis of the sample. This being the case, down hole samples are usually preferred over surface samples, due to errors which accumulate during separation at the well site, remixing in the lab, and the differences in measuring instruments and techniques used to mix the fluids to a composition that represents the original reservoir fluid. However, down hole sampling can also be costly in terms of time and money, such as when sampling time is increased because sampling efficiency is low.